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Oct. 11, 1932. F. o. MUELLER CALCULAIING MACHINE Filed June 13, 1928 5 Sheets-Sheet 1.1-, rumuuila INVENTOR Wade/7'01 (7270 flaw/10,2

c /fim 7%eu? ATTORNEYS Oct. 11, 1932. F. o. MUELLER CALCULATING MACHINE Filed June 13, 1928 5 Sheets-Sheet 2 Oct. 11, 1932. F. O/MUELLER CALCULATING MACHINE Filed June 13. 1928 5 Sheets-Sheet 3 INV NTOR Bacteria/b @fififiimdom @607, WW, 1

TORNEYS QMM 7 71;:

5 Sheets-Sheet 4 ATTORNEYS y F. O. MUELLER CALCILATING MACHINE Filed June 13.

Oct. 11, 1932.

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Oct. 11, 1932. F. o. MUELLER CALCULATING MACHINE Filed June 13, 1928 5 Sheets-Sheet 5 INVENTOR fl-edamlc/fi (mom uuuuuuuu n:

, aQu/w, r ha ATTORNEYS Patented Oct. 11', 1932 UNITED STATES.

PATENT OFFICE FREDERICK 0'1") MUELLER, OI DETBOI'I', MICHIGAN, ASSIGNOR T0 BUBBOUGHB ADDING MACHINE COMPANY, 01' DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN CALCULATING MACHINE Application filed June 18,

This invention relates to a calculating machine and it is directed particularly to a construction for overning the operation of such a machine w en an overdraft or negative total occurs therein.

The invention is shown a plied to a Burrou hs Moon-Ho kins machine of the type disc osed in Ho 'ns Patent Nos. 1 06,113 and 1,336,904, re erence bein especial y made to the first patent which is irected to mechanism more directly concerned with the present invention, the second patent, however, describing the general structure of the machine in detail. It is to beunderstood that the invention ma be used with any other suitable type of machine, the articular machine illustrated bein merely y way of example.

The mac ine of said Hopkins atents is a ten key machine ca able of ad ition, subtraction, multi lication and division. Subtraction is per ormed by a process of complemental addition although it is not necessary to enter the complement on the amount keys. The minuend is set up on the keys and the machine given a stroke of operation to enter the item in one of the counters. The subtrahend is set up in certain ndants by entering it on the amount keys, epressing a subtraction key and 'ving the machine a stroke of operation. he remainder is then obtained. by depressing a special key and giving the machine another stroke of operation. When the machine is operated to obtain the remainder, the pendants arrest the actuator racks in positions corresponding to the 9 complement of the subtrahend,'it bein understood that all the racks to the left of those used for the subtrahend are arrested in their 9 position. As the machine completes its stroke of operation this complement, plus one, is added to the minuend and the correct difference will be registered in the counter as lon as the minuend is greater than the subtra end. When the minuend is less than the subtrahend, as is the case when a larger number is subtracted from a smaller one, the correct remainder will not be present in the counter. Instead, the complement of the remainder will be found. Provision is made 1928. serial No. 284,918.

113 for causing a bell to ring when such condition occurs and to cause the rinting mechanism to be blocked so that t e complement of the remainder cannot be printed. The operator can then obtain the correct remainder or negative total by operating the machine in a particular manner described in said patent, which, however, involves clearing the counter. It often happens that an operator does not hear the signal or does not pay any attention to it but continues to o erate the machine. The result is that althoug the complement of the remainder is not printed, it remains in the counter and reduces error. Also, until the counter is cleared the printing mechanism will not operate. An im rovement was later made as shown in ueller Patent No. 1,715,170, whereby not only was a visual signal iven when the above condition occurred, at the motor bar was also looked so that the operator could not continue to operate the machine. This prevented further operation until a release key was depressed. A release key was provided for releasing the motor bar so that the operator could operate the machine in the required manner to obtain the correct negative total. In both the above machines however, the printing mechanism was blocked and it was necessary to go through a series of operations to clear the register and strike a balance before proceeding with the entry of subsequent items. Where a series of items are bemg entered it is not always desirable to clear the counter when a negative total exists.

g For example, even though there may be a negative total in the machine at one time, the posting of subsequent positive items may change this negative total to a positive total and, in such event, it is not desirable to have to go through a series of operations requiring a clearing of the counter. It also frequently happens that it is desired to enter a negative item when there is no positive item in the machine. In the prior constructions referred to, the entry of such negative item resulted in blocking the printing mechanism and, in the second construction, in locking the motor bar. a

The present invention is directed to a mechanism which retains the advantages of the prior constructions and eliminates their disadvantages by enabling items to be entered even though a no ative total may exist in the machine, the loc 'ng device being effective onl when an attem t is made to take a total wit a negative tot in the counter.

The ob ect of the invention is to provide an improve construction for insuring proper operation of a calculatin machine when a ne ative total exists tllBIBlIL,

more particular object is to provide a mechanism of this character, that will not onlyfive a si a1 and prevent the immediate an irect ta 'n of a total when a negative total exists in the machine, but one which will also while continuing to prevent a total being taken directly, permit the continued entry of both positive and negative items.

Another ob ect of the invention is to provide a mechanism of the character described which will not'interfere with the entry of negative items in the machine when there is no positive item in the machine from which to subtract it.

A still further object is to provide a simplified construction in a mechanism of this character so as to reduce its cost and improve its efliciency'of operation.

Other objects and advantages of the invention will appear from the specification and drawings.

An embodiment of the invention is shown in the accompanying drawings in which F i re 1 is a sectional side elevation s owing t e general features of the machine with the invention a plied thereto.

Fig. 2 is a p an view of a portion of the ke board.

ig. 3 is a rspective view of the portlons of the invcntlon associated with the counter of the machine.

Fig. 4 is a side elevation of one of the usual actuator racks used in the machine.

Fig. 5 is a side elevation of a spec1al actuator rack used with the resent invention.

Fig. 6 is a sectional side elevation of that part of the invention associated directly by the counters, the parts being shown in normal position.

Fi 7 is a view similar to Fig. 6 illustrating t e position of the parts near the end of a orward stroke of the machine, the parts be in in an overdraft condition.

ig. 8 is a view similar to 3 showing the condition of the parts when an overdraft has occurred, that is, when a larger number has been subtracted from a smaller.

Fig. 9 is a view similar to Fig. 8 showing how the printing mechanism is released after it has been locked by the negative total lock.

Fig. 10 is a partial sectional plan view of the locking mechanism for the total keys on the keyboard, the parts being shown in normal position.

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Fig. 11 is a sectional front elevation of a portion of the keyboard showing the position of the parts when one of the keys is depressed.

Fig. 12 is a sectional side elevation of a portion of the keyboard with the arts in normal condition on line 12-l2 of ig. 10.

F i 13 is a sectional sic a elevation correspon ing to Fig. 12 with the parts in the position they occu y when the keys are locked and with the over raft sign moved into view.

Fig. 14 is a view similar to Fig. 10 showing how the lock is released by depression of the release key.

The details of the machine to which the invention is applied will be described only briefl reference being made for details to the opkins patents heretofore mentioned.

General construction of machine The machine, which is of the ten key type, has a plurality of amount keys 10, two of which are shown in Fig. 2, and each of which, when depressed, rocks its respective lever 11 (Fig. 1) to thrust upward one of the push bars 12. These push bars act to project pins or setting up devices 13 in a traveling pin carriage 14 which is stepped across the machine one step at a time for each key depression. As the amount keys are depressed to enter an item in the machine, said item is set up in the traveling pin carriage by the projection of the corresponding pins 13. After the item has been set up in the pin carriage,

' the machine is given a stroke of operation which raises the carriage bodily and causes the projected pins 13 to contact and move upward corresponding stop pins 15 (Fig 6) in a stationary field of stops which is located so that when said stops are projected, they will arrest the forward movement of actuator rack bars 16 that are released for such movement by operation of the machine. The forward ends 17 of the rack bars carry types 18 which are positioned adjacent the printing line of a platen 19 as the rack bars are difierentially positioned by the stationary stops 15. After the rack bars have been positioned and before they are returned during the return stroke of the machine, a printing mechanism including hammers 20 is operated which causes the hammers to strike the types to rint theamount that has been entered. en addition is to be performed, one or more of the several counters of the machine is rocked into engagement with the racks prior to their return so that, as said racks are returned to normal, the item set up in the machine will beentered additively in the counter or counters. These counters and the mechanism for controlling them are not illustrated in detail in the present case, being fully disclosed in the Hopkins patents re ferred to. Two of the counters are shown in Figs. 1, 4 and 5, one of them being indicated at 21 and the other at 22. Totals are taken in the usual manner by rocking a counter into engagement with the racks before they are moved forward, the racks thus rotating the counter pinions to zero and the counter pinions acting to differentially position the racks so that the type bars are positioned to print the total.

In addition to the devices described the machine is provided with a series of pendants 23 slidably mounted on the arms 24 of vertically movable members 25 having stepped arms 26 for arresting movement of the actuator racks. No attempt will be made todescribe the operation of these devices in the present application as the same is rather complicated and a full description is contained 1n the aforesaid Hopkins patents. It is sufficient for the purposes of the present application to understand that, when subtraction is to be performed, the number to be subtracted is entered on the keys, a subtract key 27- is depressed, and the machine given a stroke of o eration to enter the subtrahend in these pen ants which are arranged so that they will then sto the actuator racks in positions corresponding to the 9 complement of the subtrahend, with all the actuators to the left of the ones used for registering the subtrahend positioned so as to arrest the actuator racks in their 9 positions. The

- extra one that is added to the 9 complement of the subtrahend is automatically added by a mechanism described in said Hopkins patent.

In performing subtraction by the complemental method, the pinion of highest order is always rotated from its 9 to its zero position when the minuend is larger than the subtrahend, but it is not so rotated when the minuend is smaller than the subtrahend.

In order that this may be clearly understood, P

an example will be taken.

Assume that it is desired to subtract 33 from 55. The minuend 55, is entered in the machine which is then given a stroke of operation to put the minuend in the rear counter. The subtrahend 33 is then entered on the pendants after which the machine is operated to add the complement of the subtrahend to the minuend. This means the addition of 66 plus 1, with 98 to the left of the 6, or to state the example in figures,it is as follows: a

It will be observed that the pinion of high-' est order, that is the pinion the farthest to the left, will be rotated from its 9 to its zero position in the above operation.

Now assume that it is desired to subtract 77 from 55 and that the items are entered in It will be observed that in this case the pinion of highest order does not move he ond its 9 position. Advantage is taken 0 this fact to control devices which will now be described.

Uontrollz'ng mechanism associated with the counter Mechanism is associated with the pinion of highest order to control several devices. This mechanism will'first be described after which its connections with the devices controlled will be explained.

Referring'to Fig. 3, the pinion of highest order is the pinion 30 with which 200 erates one of the usual actuator racks .16. to the left of this pinion is a special pinion 31 with which cooperates a special rack 32 that is shorter than the usual rack, as illustrated in Fig. 5. The special rack bar carries no printlng types and it has no teeth for operating the front re 'ster pinions. This bar is not indexed by t e stationary field of stop ins 15 when they are projected, but it is in exed by an extra pendant 23 whenever the subtraction key is depressed, that is,

\ whenever a subtraction operation takes place by the complemental method, the special rack 32 is indexed, by its pendant 23 so that said rack is stopped in its 9 position. A carry segment 33 of the usual construction described in said Hopkins patents is provided for transferring a unit of movement from the. inion 30 of highest order to the special pinion 31. Accordingly, whenever the pinion of highest order moves from its 9 to its zero position, a carry takes place which moves the special pinion 31 one step. 4 Fixe to the special pinion 31 is a sleeve 34 car. inga cam disk 35 having a notch 36 in its dge. Bearing against the edge of the cam disk 35 is a roller 37 mounted on the end of an arm 38 pivoted on the stud 39, said arm being urged in a counter-clockwise direction b a spring 40, one end of which is connecte to a stationary stud 41 and the other end to a stud 42 on the arm 38. The stud 42 pro'ects beneath an extension 43 of 'an arm 44,wh1ch is also pivoted on a stud 39. The arm 44 is yieldingly connected with the arm 38 by means of a sprin 45, one end of which is connected to the stu 42 and the other end to a stud 46 on the arm 44. It will be noted that, by means of this connection between the two arms,whenever the arm 38 is moved countor-clockwise its stud 42 positively moves the arm 44 with it, but, at the same time, the arm 44 can move counter-clockwise independounted end of the arm 44 has a hooked-shaped nose 47 ada ted to engage a stud 48 on an arm 49 of a yo (e 50 pivoted at 51 and having a rearwardly extending arm 52 to which one end of the spring 53 is connected, said spring serving to urge the yoke 50 in a clockwise direction. Connected to the arm 52 is a link 54 which extends downwardly as illustrated in Fig. 1 to control certain locking devices, but before describing said devices, the operation of the above described mechanism will be briefly explained.

Whenever the special pinion 31 occupieswhat may be termed the zero position, the cam slot 36 is opposite the cam roller 37 and said cam roller seats in said slot as illustrated in Fig. 6. In this position of the parts the hook nose 47 of the arm 44 is above the stud 48, the parts having been moved to this position under the influence of the spring 40. Whenever the special pinion 31 is moved away from its zero position, the arm 38 is cammed clockwise which, through the spring connection 45, moves the arm 44 clockwise to position the hook -nose 47 in the path of the stud 48 as illustrated in Fig. 7. From. this it will be observed that, whenever a subtraction operation takes place, which, as previously described, results in indexing the special rack 32 in its 9 position, the pinion 31 will be rotated to its 9 osition on the return stroke of the mac ine and the nose 47 will be moved into the path of the stud 48, except that, if a carry takes place, as it would when a smaller number is substracted from a larger, the pinion 31 is moved. and added step to its zero position whereupon the spring 40 snaps the arm 38 counter-clockwise to move the roller 37 into the notch 36 and move the nose 47 out of the path of the stud 48. In other words whenha smaller number is substracted from a larger the'parts are positioned so that the nose 47 is above the path of the stud 48, but when a larger number is subtracted from a smaller so that a carry does not take place from the pinion of highest order, the nose 47 is in the path of the stud 48.

The mechanism above described controls certain lockin g devices on the keyboard which willnow be described.

Key locking connection Provisionis made for locking the several total keys 55, 56 and 57 at the front of the machine, which are sometimes referred to as the balance keys, said keys being marked Bal Or bal and Sub bal in Fig. 2.

Referring to Fig. 1, the link 54 is connected to an arm 60 fixed to a shaft 61. The free end of the arm 60 carries a cam roller 62 which, under certain conditions, is acted upon by a cam 68 fixed to the main driving shaft 64 of the machine. When the subtract key 27 is depressed, the shaft 61 is moved laterally by connections described in the Hopkins patents so as to position the cam roller 62 in alignment with the cam 63. The shaft 64 with the cam 63 is rocked clockwise during the forward stroke of the machine and returned counter-clockwise upon the return stroke. Accordingly, when the subtract key is depressed and the machine is given a stroke of operation, the cam 63 acts on the roller 62 and rocks the arm 60 clockwise to pull downwardly on the link 54 which rocks the yoke 50 counter-clockwise against the tension of its 5 ring 53. Upon the return stroke of the mac ine the cam 63 frees the arm 60 so that the spring 53 may return the parts to normal position. I

Pivoted on a standard 65 projecting from the machine bar adjacent the arm 60 is a bell crank lever one arm 66 of which has a lug 67 located in the path of the arm 60 and the other arm 68 of which is connected to a rod or link 69 that extends to the front of the machine as illustrated in Fig. 1. The rod 69 is urged forward by a spring 70 which keeps the bell crank lever positioned so that its lug 67 contacts the bottom of the arm 60.

The forward end of the rod 69 is connected to one end of a lever 71 pivoted to a base standard at 72. Also connected to the for ward end of rod 69 is a plate like extension 73 slidably mounted upon the keyboard plate 74 and provided with an enlarged signal portion 75 bearing the characters 0. D. meaning overdraft (F i 2), said signal being normally position out of sight beneath an overdraft release key 76. The end of the lever 71 opposite to that connected to rod 69 carries a stud 77 normally occupyin the vertical portion of a slot 78 in a sli e 79. This slide is ur d rearwardl and downwardly to a position to keep t e stud 77 in the vertical portion of the slot 78 by a spring 80, one end of which is connected to a projection on the slide and the other end to the stud 72 on which the lever 71 is pivoted.

Slidabl mounted on the base plate 81 (Fig. 10) is a ocking slide 82 having a series of upstanding pro ections 83, 84 and 85 each of which has a beveled ed e as illustrated in Fig. 11. This locking ide is urged to the left as shown in Figs. 10 and 11 b means of a spring 86 connected at one en to a stud on the base plate 81 and at the other end to the slide 82. This spring normally maintains the slide in such position that the bevele'd edges of its projections 83, 84 and 85 are under the respective bell crank levers 87', 88 and 89 that are rocked counter-clockwise whenever their respective total keys 55, 56 or 57 are depressed. When one of these ke s is depressed, its bell crank lever engages the beveled edge of its respective rojection on the locking slide 82 and said ide is moved to the right against the tension of its spring 86. a

The slide 79 is mounted in a'slot in a member 90 fixed to the base plate 81 so that said slide cannet move sidewise. Said slide carries an abutment 91 on its inner side (Fig. 10) which, when the slide is moved forwar moves into the path of the locking slide 82 to block the latter. Whenthis occurs the locking slide 82 cannot move to the right and all three "of the keys 55, 56 and 57 are locked against depression.

The operation of the key locking parts thus far described is as follows:

When the subtraction key 27 is e ressed and the machine is 'ven a stroke 0 o eration, the cam 63 r the arm 60 cloc 'se which pulls rearwardly on the link 69 and swings the lever 71 clockwise (Fig. 13) Movement of lever 71 moves the overdraft signal 75 out from under the overdraft release key 76 so that said signal is visible and, at the same time, it moves the slide 79 forward so that its abutment 91 is in the path of the lockin slide 82. During the forward stroke of t e machine, the overdraft signal thus comes into view and the keys 55, 56 and 57 are locked against de ression. As the arm 60 moves down during 51c forward stroke of the machine, the link 54 is pulled downward and the oke is rocked counter-clockwise from its i 6 to its Fig. 7 position. If

'- the nose 47 she d happen to be in the path of the stud 48, the stud will pass it because the beveled end of nose 47 will ride over the stud, the spring 45 yielding to rmit such action. The stud 48 thus moves ack of the hooked nose 47 to the Fig. 7 position. If the amount subtracted does not create an overdraft or a negative total in the counter the slot 36 in the cam disk 35 registers with the cam roller 37 and the book 47 is moved above the stud 48 so that the yoke 50 to which the link 54 is connected is free to return clockwise to its normal position under the influence of the spring 53 on the return stroke. When this occurs the rod 69 is freed so that its sprin may move it forward again, said forwa movement resulting in movin the slide 79 out of its blockin position and in movin the overdraft signal backunder the over ft release key 76. It will thus be noted that during each operation of the machine in r.-

forming subtraction the total keys am loc ed and the overdraft signal comes into view, but the keys are unlocked and the overdraft signal is hidden again if no negative total occurs.

If, however, the number subtracted is lar er than the number from which it is subtracted, the slot 86 will not re r with the cam roller 37 and the hook -nose 47 be maintained in the path of the stud 48. Whenthe cam 63 frees the arm 60, said arm cannot move upwardly to its normal osition owing to the fact that the yoke 50 is locked in its rearward position as illustrated m Fig. 8. This maintains the link 69 in its rearward position and keeps the slide 79 in its blocking position, the overdraft signal 75 also bei'n maintained in its visible position Accor ingly, all three of the total keys 55, 56 and 57 are locked against de ression and the overdraft signal is a ed. In other words, whenever an over ra nal is displayed and all the total or balance keys are locked against depression. This condition remains as long as the overdraft exists, the condition being illustrated in Fig.

occurs, a sig- 8. The link 54 car not return to normal, but

this does not interfere with the entry of items. .Instead, it keeps the balance keys locked and controls the printing mechanism as will be described later.

Release key ed by depression of the overdraft release key 76. a

The release key 76 is normally blocked a ainst operation by the overdraft signal 75 w 'ch ro'ects beneath it. The key is released urmg each operation of the machine in performing subtraction, but it is blocked again'unless an overdraft occurs, in which event, the overdraft si al is held in the position illustrated in Fig. 13 which frees the release key for depression.

The release key is urged u wardly by a spring surrounding the key stem 101. The lower end of said stem has. a slot 102 in which projects a branch 103 of the slide 79. The slide 79 has a projection 104 in its lower edge which rests on the base plate 81 and forms a fulcrum about which the slide 79 may be rocked. When the release key 76 is de re'ssed after a negative total occurs, the sli e 79 is rocked counter-clockwise which moves its rear end upwardly to free it from the stud 77 on lever 71, whereupon the ring 80 snaps the slide 79 rearwardly, ass own in Fig. 14, to move the abutment 91 out of the path of the locking slide 82, thereby releasing the keys 55, 56 and 57. The rod 69 "still remains in its rearward podtion and Y b its sprin tli e g 70. As rod 69 moves forward, lever 71 1s rocked counter-clockwise from the position of Fig. 14 to that of Fig. 12 which moves the stud 77 opposite the vertical portion of the slot 78, whereupon the spring 80 which has a slight downward pull on the slide 79 pulls said slide downward to normal position with' the stud 77 in the vertical osition of the slot 78, thereby positioning t 8 parts in normal and in condition for another operation.

The blocking of the release ke 76 against operation when no negative tota occurs prevents misoperation of the mechanism. If the key 76 were depressible when the parts are in their Fig. 12 position, that is, normal, the slide 79 would be rocked counter-clockwise so that the stud 77 would be in the horizontal portion of slot 78 of slide 79. The sprin 80 might then move slide 79 rearward enoug since the slide has no fixed pivot, to cause it to catch over stud 77. If this should occur then, when a negative total occurred and t e lever 71 rocked clockwise, it would not move slide 79 forward because stud 77 would simply move in the horizontal portion of the slot 78 in slide 79. The result would be that the total keys would not be locked even though a negative total had occurred. Such misoperation is prevented by the block- 4 ing of the release key against depression except when'a negative total has occurred.

Uontrol of prinJi/ng mechanism .This blocking of the printing mechanism is necessary to prevent the printing of complements and undesired figures during the operations of the machine that are necessary to condition it to print the true negative total.

If, when a negative total occurs, the total key were depressed and the total printed, the figure would be the complement of the true negative total. To prevent this both the total key and the printin mechanism are locked. But to get the mac ine in condition to print the true negative total, the total ke must be depressed and the machine 0 erate which transfers the complement of t e negative total to the ndants at the'rear of the In or er that the total key may be depressed a release key is provided for releasing it, but this release key does not release the. rinting mechanism. Accordingly, the comp ement of the true negative total 18 not "printed during its transfer to the pendants. After the' transfer of this complement,'the subtract key is depressed and the machine operated to subtract the complement of the negative total from zero, that 15, from one of the registers that is clear. This uts the true negative total in said registen t is not desired to print the subtracted figure so the rinting mechanism rema ns locked. After t is subtraction operation, a total is taken from the register and printed, the total being the true negative total. The printing mechanism is automatically released for printing of this true total by mechanism described 1n detail in Hopkins Patent No. 1,206,- 113, but it is not rciased prior to that time. The present invention provides a further control of the printing mechanism whereby it can be automatically released, after a negative total occurs, by the entry of items in the machine. The total key remains locked but the printing mechanism is temporarily unlocked to permit the items to be entered.

Referring to Fig. 6, the yoke 50 has a downwardl extendin arm 110 provided with a stu 111 operating in a slot 112 in a link 113, slidably mounted on. a. frame stud 114. The link 113 is urged forward by a spring 132 connected at one end to the stud 111 and at the other end to a stud 115 on the link. The stud 111 thus normally occupies a position at the rear end of the slot 112. The forward end of the link 113 has an upstanding projection-116 (Fig. 1) adapted to engage a stud 117 onan arm 118 that controls the blocking of the printing hammers 20.

As the yoke 50 is rocked counter-clockwise at each operation of the machine during subtraction, the link 113 is yieldingly moved forward to block the printing hammers and, if

- an overdraft occurs which results in latching the yoke 50 in its counter-clockwise position, the link 113 is held forward to block the printing hammers. In this manner the printing mechanism is blocked when an overdraft occurs so that said overdraft will not be printed. The release of the total keys by means of the release key 7 does not release the printing mechanism as there is no connection between said release key and the printin mechanism. Said printin mechanism, is released, however, after t e total ke s are released. by operation of the machine in the manner described in said Hopkins Patent #1,206,113 to obtain the correct negative total, but the resent invention concerns means for releasing it without requiringghat a total be taken.

previously explained, it is often desirable to continue posting items even though a negative total may exist because the positive items that are entered may eventually cancel the negative total before it is necessary to actually'strike a balance or take a total on the machine. If the machine becomes locked whenever a negative total occurs so that it is necessary to strike a balance before being able to proceed, the speed of operations is interfered with and the work 1s also mixed up. Accordingl provision has been made for automatica ly releasing the printing mechanism by the entry of items in the machine 120 (Figs. 6 and 9) is a plate 121 urged downward by a spring 122. The lower end of this plate is positioned so that, when the pin carriage 14 is raised, said carriage engages the end of the plate to move it upwardly. The upper end of the plate has a beveled nose 123 positioned to engage a stud, 124 on a projection on the link 113. When the parts are in the normal position illustrated in Fig. 6, the link 113 is in its rearward position where the stud 124-is outof the path of the nose 123. During each operation of the machine in addition the plate 121 is raised but since the link 113 is not moved forward there is no coaction between nose 123 and stud 124. During a subtraction operation the link 113 is moved forward from its Fig. 6 to its Fig. 7 position which blocks'the printing mechanism momentarily. If no negative total occurs, the link 113 returns rearward, frees the printing mechanism and moves the stud 124 out of the path of nose 123. However, when a negative total occurs and the'link 113 is latched in its forward position illustrated in Fig. 8, as previously described, the stud 124 is in contact with the beveled edge of the nose 123. This keeps the printing. mechanism .blocked against printing the complement of the negative total but if an item is entered, and the machine is given a stroke'of operation, the raising of the intermediate pin carriage 14 will push the plate 121'upwardly whereupon the nose 123 will cam the link 113 rearwardly to automatically release the printing mechanism- The position of the parts when this occurs is illustrated in Fig. 9. This release occurs for the entry of both positive and negative items as the pin carriage is raised in the entry of both kinds of items.

In order to prevent the link 113 from being released too quickly by the immediate descent of the pin carriage 14, a latch 125 is provided which is urged clockwise by a spring 126. In the normal position of the parts illustrated in Fig. 6 this latch contacts the face of the nose 123 which holds it in the position there shown. When the slide 121 is raised to-the position of Fig. 9, the spring 126 moves the latch 125 clockwise under the shoulder 127 formed on the slide 121 by the nose 123; Accordingly, when the slide 121 is released by the descent of the carriage 14, it descends a short distance, but not to such a point as to release the link 113. Instead, the shoulder 127 contacts the end of latch 125 and the slide 121 is held upward to maintain the link 113 rearward in practically norinal position, that is, in a position to permit the printing mechanism to operate.

The machine is provided with the usual comb-plate 130 which is urged upwardly by a spring 131. This comb-plate restores the stop pins 15 and it is o erated near the end of the return stroke 0 the machine. plate and the mechanism for operating it are described in detail in said Hopkins patents. The tail of the latch 125 is positioned under this comb-plate as illustrated in Figs. 6 and 9 so that, when the comb-plate is moved down, the latch is swung counter-clockwise to release the slide 121. Accordingly, near the end of the return stroke of the machine the slide 121 is released from hammer block condition so that it can be moved back to normal by its spring 122.

It will thus be clear that even though a negative total exists in the machine and the printing mechanism is blocked against printing the complement, of the negative total, nevertheless, said printing mechanism is automatically unlocked whenever an item is entered and the machine is given a stroke of operation. As many items as desired may be entered and, in each case, the items will be printed, the printing mechanism being unlocked each time the machine is operated.

This

This may occur while the balance keys remain locked. In other words, the machine is free to permit the entry of items, but a balance cannot be taken because there is a negative total in the machine. Should the entry of the items cancel the negative total,- then the balance keys will be unlocked and the machine is free. The advantage of this construction willbe obvious. It provides a lock against the taking of a total when there is a negative total in the machine, and notifies the operator that a negative total exists so that he may operate the machine properly to get the negative total printed accurately. This lock, however, does not interfere with the entry of ordinary items and, if these items should cancel the negative total, the machine becomes entirely unlocked. all this occurring without requiring manipulation of any spe-I cial keys or any special manipulation of the machine.

The above construction also permits the entry of negative items in the event there is no balance in the machine. Such items are entered by depressing the subtract key and the action, as far as the counter is concerned, is the same'as if a negative total existed. This would result in locking the printing mechanism were it not for the fact that the devices above described automatically unlock it when the pin carriage is raised. a

It is to be understood that the structure shown is for purpose of illustration only and that variations may be made in it without departing from the spirit and scope-of the invention as-defined by the appended claims.

I claim:

1. The combination in a machine of the class described havin a counter and a total taking means inclu ing manipulative devices adapted to condition the machine to take a total, of a locking means conditioned automatically by the counter when a negative total occurs therein for locking the manipulative devices against operation, means for releasing said locking means, and a signal device normally hidden by said releasing means and normally preventing operation thereof, said locking means having connections to said signal device which operate it to release the releasing means and display the signal when the locking means is operated to lock the manipulative devices.

2. The combination in a machine of the class described having a counter and a totaltaking means including a balance key adapted to be depressed tmcondition the machine to take a total, of a locking means conditioned automatically by the counter when a negative total occurs therein for locking the balance key against de ression, a depressible release key for re easing said locking means, and a signal device normally hidden beneath said release kc and actin to prevent depression of said key sai locking means being connected to said signal device to move it to a visible position and to a position to release the release key when the looking means is operated to lock the balance ke The combination in a machine of the class described having a counter, a printing mechanism, and amount determining devices upon which items may be entered to be registered in the machine, of a locking means conditioned automatically b said counter when a negative total occurs t erein for looking said printing mechanism against efiective operation, and means acting automatically when the machine is operated to enter items therein for temporarily releasing said printing mechanism.

4. The combination in a machine of the class described having a counter, a printing mechanism, amount determining devices upon which items may be entered to be registered in the machine, and a restoring device for restoring arts of the machine to normal at the end 0? its operation, of a looking means conditioned automatically by said counter when a negative total occurs therein for locking the printing mechanism a ainst operation, means operating automatica lly as the machine is operated to enter items for temporarily releasin said tinting mechanism, a latch for hold n said printing mechanism in temporarily re eased condition, and connections operated by said restoring device for releasing said latch when the restorinlg device is operated. 5. h

e combination 11? a inachine of the class described having a counter, a printing mechanism, and a pin ci-rriage which is moved at each operation of the machine when items are entered therein, of a lockin means conditioned automatically by sai counter when a negative total occurs therein for locking said printing mechanism against operation, and means operated automatically by said pin carriage when the same is moved during the entry of items in said machine for temporarily releasing said printing mechanism.

6. The combination in a machine of the class described having a counter, aprinting mechanism, a pin carriage which is moved asthe machine is operated to enter items therein, and a restoring device for restoring to normal at the end of each operation of the machine certain parts of the machine set by said pin carriage, of a locking means conditioned automatically by the counter when a negative total occurs therein for locking the printing mechanism against operation, means operated by said pin carriage as it is moved during the entry of items in said machine for temporarily releasing said printing mechanism, a latch for holding said printing mechanism in released condition, and connections between said restoring device and said latch for releasing said latch as the restoring device is operated.

7. The combination in a machine of the class described having a counter, amount determining devices by means of which items may be entered in the machine, a printing mechanism, and total-taking means including manipulative devices by means of which the machine may be conditioned for total taking, of a locking means conditioned automatically by said counter when a negative total occurs therein for locking said manipulaiive devices against operation, said locking means including connections for locking the printing mechanism against effective operation,

and means operating automatically when said machine is operated to enter items therein after said negative total occurs to temporarily release said printing mechanism for the printing of items.

8. The combination in a machine of the class described having a counter, amo nt determining devices by means of which items may be entered in the machine, a printing mechanism, and a total-taking means including a balance key which may be depressed to condition the machine to take a total. of a locking means conditioned automatically by said counter when a negative total occurs therein for locking said balance key against depression, said locking means including connections for locking said printing mechanism against effective operation, and means operated automatically as the machine is operated to enter items therein 'for temporarily releasing said printing mechanism for item printing while leaving the balance key locked, whereby items may be entered in said counter and printed whi e a negative total exists therein, said locking means actin automatically to fully release the balance ey and the printing mechanism when said negative total is changed to a positive total by the entry of items subsequent to the existence of a negative total.

9. The combination in a machine of the class described having actuator racks, a counter comprising a plurality of counter pinions mounted upon a shaft and a transfer mechanism, of an extra counter pinion mounted on said shaft adjacent the pinion of highest order, an actuator rack for said extra pinion, a transfer awl for said extra pinion connected with t transfer mechanism for said counter, a cam plate mounted upon said shaft and connected to said extra pinion, said cam plate being provided with a notch, and a locking means for locking certain portions of the machine against operation, said locking means being normally moved to and from locking position at each sub-traction operation of the machine, said locking means including connections normally engaging the notch in said cam plate when the extra pinion is in zero position, said cam acti to move said connections to prevent said ocking means from returning to unlocked position as the machine is operated when the extra pinion does not move to zero position.

10. The combination in a machine of the class described having actuator racks, a counter com rising a plurality of counter pinions mounted upon a counter shaft, and a trans- .fer mechanism, of a locking means moved to and from locking position at each subtraction operation of the machine to lock certain portions of the machine against movement, an extra pinion mounted on said shaft adjacent the pinion of highest order, an actuator rack for said extra pinion, a transfer pawl for said pinion connected to the transfer mechanism of said counter, a cam plate journaled on said shaftand connected to said extra pinion, said cam plate having a notch in its edge, and a latch for said locking means having an arm carrying a cam roller urged into enga ement with the edge of said cam plate, the roller engaging in said notch when the extra pinion is in zero position, said latch being out of the path of said locking means when the roller engages the notch in the cam plate but being may be entered in the machine, a total taking means, and a printing mechanism normally 0 erated durin each operation of the mac ine, of a-lockmg means conditioned automatically by said counter when, a negative total occurs therein to lock said printing mechanism against total printing operation until said machine has been operated in a predetermined manner, said means operating automatically when said machine is operated to enter items therein after a negative total occurs to temporarily release said printing mechanism for item printing without releasing it for total printing.

n testimony whereof, I have subscribed y name.

FREDERICK OTTO MUELLER.

positioned to prevent the returnpf the lock- 1n means to unlocked position when the ro er is out of said notch.

11. The combination in a machine of the class described'having a counter, amount determining devices by means of which items CERTIFICATE OF CORRECTION.

Patent No. l.88l,852.- October 11, I932.

FREDERICK orro MUELLER.

lt-is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 9, line 74, claim 11, for "said" read "and"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 13th day of December, A. D. 1932,

M. J. Moore, (Seal) Acting Coumiasioner of Patents. 

